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Lexicon Pharmaceuticals, Inc. (Nasdaq: LXRX), a biopharmaceutical company focused on discovering breakthrough treatments for human disease, announced today that it has successfully completed a Phase 1 clinical trial of LX1033, an orally-delivered small molecule drug candidate for diarrhea-predominant irritable bowel syndrome (IBS-d). Lexicon plans to move LX1033 forward into a Phase 2 study in patients with IBS-d.

Top-line results demonstrated that LX1033 was well tolerated at all doses and produced a statistically significant reduction in serotonin synthesis compared to placebo, as measured by both plasma (p
"Based on the completed LX1033 Phase 1 program, we are confident that a convenient dose regimen of this compound can provide the level of serotonin reduction that we have previously associated with clinical benefit for patients with IBS-d," said Dr. Brian Zambrowicz, chief scientific officer at Lexicon. "We were also impressed by the performance of the blood test for measuring 5-HIAA and anticipate using this biomarker to guide future drug development of LX1033."

The LX1033 Phase 1 trial was conducted as a randomized, placebo-controlled trial in healthy volunteers. In the multiple ascending dose portion of the study, doses of 250 mg, 500 mg, and 750 mg given three times daily, as well as 1,000 mg given twice daily, were administered over the course of 14 days. There were eight healthy volunteers (six receiving active compound, two receiving placebo) in each dose group. Study endpoints included safety and tolerability together with pharmacokinetic and pharmacodynamic parameters consisting of measures of both plasma and urinary 5-HIAA. Data from the study showed that LX1033 produced a statistically significant decrease in both plasma and urinary 5-HIAA as compared to placebo at all doses tested. Notably, the plasma measures of 5-HIAA in the recent study were obtained from a simple morning blood draw and correlated with results obtained by the traditional 24-hour urine collection method.

"The favorable safety and tolerability profile for LX1033, together with its local site of action within the gastrointestinal tract and ability to potently reduce serotonin synthesis, make this a very attractive candidate for clinical trials in IBS-d, where the need for new treatments is great," said Dr. Pablo Lapuerta, senior vice president and chief medical officer at Lexicon. "We look forward to advancing this drug into a Phase 2 trial where we can examine safety and efficacy in IBS-d."

About LX1033

LX1033 is an orally-delivered drug candidate for IBS that inhibits tryptophan hydroxylase (TPH), a key enzyme in the synthesis of serotonin. LX1033 is designed to act locally in the gastrointestinal (GI) tract by reducing the serotonin available for receptor activation, without affecting serotonin levels in the brain.

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